During cutting operations discussed above, a large amount of dusts and/or debris may be generated from cutting area. In order to satisfactorily maintain a working environment, it is necessary to prevent the generated dusts and/or debris from being scattered around. Owing to this, during the cutting operations, a dust collection cover (a dust collector) is attached to a cutting device. A technique relating to the dust collection cover (dust collector) is disclosed in the following patent documents.
Japanese Laid-Open Patent Publication No. 2007-30314 discloses a dust collection cover which supports a cutting device having a rotary cutting blade such as a diamond cutter so as to be vertically moved with respect to a fixing cover supported on a base with which a cutting surface of a material to be cut is brought into contact. According to this dust collection cover, a grooving operation or a cutting operation can be performed by moving the rotary cutting blade within the fixing cover downward so as to protrude below a bottom surface of the base and then cutting a material to be cut with the protruding portion of the rotary cutting blade. This type of cutting is called a plunge cut.
U.S. Patent Publication No. 2008-0244910 discloses a dust collection cover used for the same kind of a cutting device, especially a dust collection cover with a double structure which supports a main body cover attached to a cutting device so as to be moved in an upward and downward direction with respect to a fixing cover supported on a base with which a cutting surface of a material to be cut is brought into contact. In the dust collection cover with the double structure, a cutting operation such as grooving can be performed by moving the cutting device together with the main body cover downwards so as to protrude the rotary cutting blade below a bottom surface of the base and then cutting a cutting surface of a material to be cut with the protruding cutting blade. According to the dust collection cover with the double structure, the main body cover is overlapped with the fixing cover, and accordingly, compared to the former dust collection cover, a higher sealability (high dust collection efficiency and/or strong dust collection power) of the dust collection cover with respect to the dusts and/or debris generated around a tip of the rotary cutting blade can be obtained along an overall vertical movable range of the rotary cutting blade.
However, it has been necessary to further improve the above latter dust collection cover with the double structure. In the prior art disclosed in U.S. Patent Publication No. 2008-0244910, high sealability can be obtained, but there is a problem that operability in exchanging a rotary cutting blade etc. may not be good enough. Generally, as is conventional in this type of dust collection cover, in order to exchange the rotary cutting blade, it is necessary to expose an attachment portion of the rotary cutting blade (a tip part of a spindle) by moving the cutting device upward. However, it has been difficult to obtain an enough operation area (exposed area) for attaching and/or detaching the rotary cutting blade etc. Furthermore, the attaching and/or detaching operation by use of, for example, a hexagon wrench or a spanner has been awkward and troublesome for a user.
In the prior art, in order to improve operability in exchanging the rotary cutting blade, a technique was disclosed such that a fixing cover is separated from a main body cover to expose the rotary cutting blade to a large extent. However, in the prior art, it sometimes happened that the fixing cover was accidentally separated from the main body cover when the dust collection cover was carried together with the cutting device. Furthermore, measures for preventing such defects was not sufficient.
Thus, there is a need in the art to provide measures to prevent the dust collection covers from being accidentally separated from each other, thereby improving operability mainly in exchanging the rotary cutting blade.